Air circuit breaker



y 6 1 A. J. GOODWIN 2,833,886

AIR CIRCUIT- BREAKER Filed March 29 1954 a Sheets-Shet 1 INVENTOR ANATOLE J. GOODWIN ATTOR 5V5 y 6, 1958 A. J. sooowm 2,833,886

AIR CIRCUIT BREAKER Filed March 29, 1954 8 Sheets-Sheet 2 INVENTOR ANATOLE J. GOODWIN BY .l-. 3,61.

ATTORN May 6, 1958 A. J. eooowm.

AIR CIRCUIT BREAKER 8 Sheets-Sheet 3 Filed March 29, 1954 INVENTOR ANATOLE J. GOODWlN gar-roan s y 6, 1958 r A. J. GOODWIN 2,833,886

AIR CIRCUIT BREAKER Filed March 29, 1954 s Sheets-Sheet 4 INVENTOR ANATOLE J. GOODWIN y 6, 1958 A. J. GOODWIN 2,833,886

AIR CIRCUIT BREAKER Filed March 29, 1954 8 Sheets-Sheet 5 INVENTOR ANATOLE J. GOODWIN y 6, 1 A. J. GOODWIN 7 2,833,886

AIR CIRCUIT BREAKER Filed March 29, 1954 8 Sheets-Sheet e INVENTOR ANATOLE J. sooowm iv 7 a Q.

ATTORNE A. J. GOODWIN AIR CIRCUIT BREAKER May 6, 1958 8 Sheets-Sheei 7 Filed March 29, 1954 INVENTOR .ANATOLE J. GOODWIN I, 1 ATTORNEYS y 6, 1958 A. J. GOODWIN 2,833,886

AIR CIRCUIT BREAKER Filed March 29, 1954 8 Sheets-Sheet 8 INVENTOR ANAi'OLE J. eoopwm av SMW a 6. ATTORN United States Patent AIR CIRCUIT BREAKER Anatole J. Goodwin, West Vancouver, British Columbia, Canada Application March 29, 1954, Serial No. 419,221

25 Claims. (Cl. 200-106) This invention relates to improvements in air circuit breakers.

An object of the present invention is the provision of a' circuit breaker having operating mechanism that will keepit firmly closed and yet which may be quickly and easily tripped when desired or as a result of an overload or short circuit.

A further object is the provision of a circuit breaker which will easily trip even under severe atmospheric conditions and/ or after long periods in the closed position.

A further object is the provision of a circuit breaker having a tripping mechanism which operates as easily under short circuit currents as it does normally.

' Yet another object is the provision of a circuit breaker which will always move to a completely closed or completely. open position without danger of stopping between said positions.

' A still further object is the provision of a circuit breaker including means for preventing rebounding of the contacts when the latter are forcefully opened as a result of a short circuit.

A circuit breaker according to the present invention includes a spring-loaded main contact block and suitable linkage for moving this block towards and away from stationary main contacts. An auxiliary spring arrangement is provided for assisting in moving the contact block away from the stationary contacts. The linkage is so arranged that the spring of the contact block exerts forces that maintain the contacts closed, that is, the contact block against the stationary contacts. Two substantially aligned and pivotally connected links which are pivotally mounted at their outer ends are maintained over a central toggle line extending between their outer pivots against a stop by the two springs so that there is no danger of the contacts being accidentally opened, At the same time,

another portion of the link arrangement is removably held in position by a tripping arm so that the switch is tripped merely by displacing said aim to allow this link portion to move out of position, after which the main block and auxiliary springs exert sufficient force to open the contacts. The tripping arm may be displaced either manuallyv or as a result of an overload or short circuit in the circuit controlled by the breaker.

The tripping arm may be displaced manually when it is desired to open the contacts, or automatically by a suitable relay when the circuit controlled by the breaker is subjected to overload or a short circuit. The magnetic field created by a short circuit tends to open the contacts with great force. The linkage of the breaker is arranged so that this great force does not interfere with the automatic tripping of the breaker. In addition to this, a latch is provided to retain the contact block in the open position regardless of the speed at which it reaches this position, thus preventing bounce or rebound.

When the tripping arm is displaced, the two links which are retained over their toggle line when the contacts are closed are moved to the opposite side of said line or the latter is shifted across the links. A suitable arrangement is provided for latching the breaker by returning the portion of the linkage to the position where it is held in place by the tripping arm, and moving the toggle links back over the toggle line thereof. For this purpose, a handle arrangement is provided which is designed to produce maximum leverage when most force is required to reset or close the breaker. In addition to this, the breaker cannot be opened by movement of the handle arrangement.

The circuit breaker may have a centre compartment and two side compartments arranged side by side. The side compartments are identical and are very similar in construction to the centre compartment, while the latter includes the latching mechanism for all compartments.

Figure 1 is a front elevation of the circuit breaker with most of the front of the casing broken away, and with one of the side compartments removed.

Figure 2 is a vertical section through the breaker taken on the line 2-2 of Figure 1, showing the mechanism of the centre compartment in side elevation, and with the breaker in the open position,

Figure 3 is a fragmentary view similar to Figure 2 with the breaker in the closed position,

Figure 4 is a section taken on the line 4--4 of Figure 2 showing the centre compartment only,

Figure 5 is a fragmentary section taken on the line- F of Figure 1, showing the mechanism of a side compartment in side elevation and in the open position,

Figure 9 is an enlarged fragmentary detail of part of the tripping mechanism,

Figure 10 is a perspective view of a tripping shaft for the breaker,

Figure 11 is a fragmentary view showing the operating handle out of its normal position,

Figures 12 to 14 are diagrams illustrating means for locking the operating handle of the breaker in position when the latter is closed, and

Figures 15 to 18 diagrammatically illustrate the various positions of the linkage during operation of the breaker.

Referring to the drawings, a vertical supporting wall 10 is formed of any suitable insulating material, such as,

black ebony asbestos board. A cover or housing 11 of any suitable design is provided. A centre compartment 15 and side compartment 16 on each side thereof are" mounted on the Wall 10 and project inwardly therefrom,

see Figure l, the right hand compartment being removed from this figure. As the two side compartments are identical, they have been given the same reference numoral, and only one will hereinafter be described in detail. This may be a 2-pole or a 3-pole breaker. If it is a 3- pole breaker, as illustrated in the drawings, there are movable and stationary main, secondary and arcing contacts in each compartment, but if it is a 2-pole breaker,

with pin 22 located near the supporting wall 10 substan tially midway between the top and bottom of the side Patented May 6,1958,-

, 3 walls 20, pin 24 spaced inwardly and upwardly from pin 22, and pin 26 spaced downwardly and inwardly from the latter pin.

A supporting component 28 is pivotally mounted on pin 22 and extends upwardly therefrom. This component includes two spaced side plates 29 which are substantially triangular in shape, the pin 22 being located near one corner thereof. A main moving contact block 30 has pins 31 projecting laterally therefrom and riding in short slots 32 formed in the side plates of the supporting component adjacent another corner thereof. This block has spaced upper and lower contact points 34 and 35, respectively.

A frame 38 is pivotally mounted by a pin 39 on the side plates 29 of the supporting component adjacent the remaining corner thereof, and projects upwardly from said plates. A portion of this frame extends downwardly between the plates and has pins 43 projecting outwardly therefrom through short curved slots 41 in the side plates, the centre of curvature of said slots being the axis of pin 39. A main spring 43 extending between the main contact block 30 and the lower end of the frame 33, see Figure 7, normally presses said members away from each other so that the pins 31 and are normally positioned at the outer ends of their respective slots.

A supporting member 45 is pivotally mounted at 46 on the outer end of frame 38. Moving arcing and secondary contacts 47 and 48, respectively, are mounted on this member. Contact 47 is above and spaced from contact 48, 'see Figures 6 and 7. A spring 49 normally urges the lower end of member 45 outwardly relative to the frame.

Spaced stationary main contacts 50 and 51 are mounted on the supporting wall 10 within the centre compartment 15. A bus bar 52 is connected to and extends downwardly from thecontact 51, while stationary arcing and secondary contacts 56 and 58, respectively, are connected to the upper contact 59. The contact 56 is connected to the main contact through a coil. 59. Terminals 62 and 63 are connected to bar 52 and contact 59, respectively. As the wiring and operation of the moving and stationary arcing and secondary contacts are well known in the art, this will not be described herein.

A connector link is pivotally connected to the supporting component 28 by a pivot pin 71 spaced above pin 22, said link extending generally downward from its pivot point. The opposite end of the link is connected by pivot pin 73 to the upper end of another connector link 74, the opposite end of which is connected by pivot pin 75 to a short toggle link 78. The lower end of the latter link is connected by pivot pin 82 to the upper end of toggle link 83, the opposite end of which is pivotally mounted on the pin 26. A stop 84 is positioned adjacent pin 82 when links 78 and 83 are substantially aligned in a vertical position. This stop is actually formed by pressing a piece inwardly from each of the side walls 20 of the centre compartment, as clearly shown in Figure 5. A lever 86 is also pivotally mounted on the pin 26, said lever having an upper portion 87 extending substantially in the same direction as link 33, the upper end of said portion beingadapted to engage the pin 82. The lever is also formed with a lower end 88 extending downwardly and. outwardly therefrom. A fairly light spring 89 connects the lever portion 87 to link 83. This spring is wound around pin 26 and has arms 90 and 91 hearing against portions of link 83 and lever 86.

An auxiliary arm 92 is pivotally mounted on pin 24, and has a downwardly extending portion or link 93, the lower end of which is connected by pin 73 to the adjacent ends of links 70 and 74. The upper portion of the arm extends outwardly from pin 24 and is connected to a transverse bar 95 formedof suitable insulating material.

A short holding link 96' is pivotally mounted on main pin 22 and extends downwardly therefrom, the free end of said link being connected by a pivot pin 97 to one end of a substantially horizontal holding link 98, the opposite end of which is connected to links 74 and 78 by pin 75. A roller 99 is mounted on pin 97.

Each side compartment 16 includes a linkage arrangement which corresponds to a portion of the linkage arrangement of the centre compartment, see Figure 8. The side compartment includes spaced side walls 100 mounted on and projecting inwardly from the supporting wall 10 parallel with the side walls 20 of the centre compartment. Walls 100 do not extend downwardly as far as walls 20, and said walls of the side compartment carry pins 102 and 103 fixed relative to each other. These pins correspond respectively to plus 22 and 24 of the centre compartment. A supporting component 106 is pivotally mounted on pin 102, and carries a main moving contact block 108 having upper and lower contacts 109 and 110, said block being mounted in the same manner and functioning in the same way as the contact block 30 of the centre comppartment. A frame 111 is pivotally mounted at 112 on the upper end of the supporting component and pivotally carries a supporting member 113 which has moving arcing and secondary contacts 114 and 115, respectively.

A link 116 extends downwardly from a pivot pin 117 carried by the component 106, the lower end of said link being connected by a pivot pin 119 to the lower end of a link or portion 122 of an arm 123 which is pivotally mounted on the pin 103. The upper portion of this arm is connected to the transverse bar 95.

It will be noted that the elements in the side compartment 16 are substantially the same as those in the centre compartment, the main exception being that links 74, 78, 83, 96 and 98 have been omitted, as well as lever 86. Another difference is that the side compartment is provided with an auxiliary spring 125 extending between a seat 126 pivotally carried by the side walls 100 and the upper portion of arm 123. In this example, the spring is wound around a bar 127 connected to the seat 126 at one end and having a slot 128 near its opposite end extending longitudinally thereof, a pin 129 carried by arm 123 extends through this slot. The auxiliary spring, bearing against pin 129, urges the bar 95 upwardly. As the arm 92 of the centre compartment is also connected to this bar, the outer end of said arm is also urged in an upward direction.

This side compartment is also provided with spaced main stationary contacts 130 and 131, bus bar 132, stationary arcing and secondary contacts 133 and 134, and coil 135.

As previously stated, the two side compartments 16 are identical. As a result of this, each of these compartments has a spring 125 which urges the opposite ends of the bar 95 upwardly. As there is a spring at each end of this bar, no twisting torque is applied to the latter.

A trip-shaft 136' journalled in the side walls 20 of the centre compartment extends through said compartment and beneath both side compartments 16. An overload relay 133 is located beneath each compartment. These relays are of well-known construction, and each has an amature 139 pivotally mounted at 140 which is attached to a core 141 under certain conditions, said core being connected to the bus bar of the compartment of the relay. The armature of each relay is designed to move a plunger 142 upwardly instantly when the breaker is subjected to a heavy overload or short circuit, but when it is subjected to a light overload, there is a time delay before the plunger moves upwardly, this time delay being caused in any desired manner, such as by a dash pot arrangement indicated at 143. A lug 144 is connected to the tripshaft for and extends over the plunger 142 of each relay and is normally spaced above the latter, see Figures 2 and 3. If desired, an adjusting screw 145 may be provided at the upper end of each plunger. When the plunger is moved upwardly, it, or the adjusting screw thereof, engages the lug and rocks the shaft against the tension of a spring 147 which tends to rotate the shaft in a counter-clockwise direction.

A tripping arm 148 is secured to and projects upwardly from shaft 136 centrally thereof near the link 96 and supporting component 28 of the centre compartment. The upper end of this arm is curved as at 149, see Figure 9, the centre of curvature of which coincides with the axis of the trip-shaft. The arm and its curved end are so located relative to link 96 that roller 99 mounted on pin 97 rests upon said curved end when the breaker is in the closed position. By referring to Figures 2, 3 and 9 it will be seen that the lower end of the arm is located to one side of the axis of the shaft, and that the arm is inclined upwardly and over the shaft to the point where it engages the periphery of roller 99. This point is always on the centre line 158 which extends through the centres of shafts 136 and pin 97, the pin centre being the axis of the roller. The curved end 149 and the left side of the arm form a sharp corner or edge 149a which is slightly to the left of centre line 150 when the main contacts are closed as in Figure 3. The movement of the upper end of the arm in a counter-clockwise direction by spring 147 is limited by an adjustable stop 151, said stop being threaded in lugs 152 projecting inwardly from a wall 20 of the centre compartment. gaged by the arm 148 or, as shown, another lug 153 may be secured to the shaft to one side of the arm, said lug projecting upwardly from the shaft and engaging the adjustable stop. Any downward pressure of roller 99 on the curved arm end does not impart any lateral component to said arm, and spring 147 normally retains the latter against stop 151.

A tripping rod 160 is movably supported in a horizontal plane and has its inner end normally spaced a little from the upper end of lug 153, as indicated at 161 in Figure 2. A button 162 is mounted on the outer end of this rod outside the casing 11. The inner end of the rod is kept away from the lug by a spring 165. When the button 162 is pressed to move rod 160 inwardly, its inner end engages lug 153 to rock shaft 136. This shaft is also rocked in the same direction if either of the plungers 142 of relays 138 is moved upwardly.

A handle arrangement is provided for pivoting lever 86 around pin 26, and is shown in Figures 2, 3 and 4. For this purpose, a vertical operating handle 175 is provided, said handle having a shaft 176 projecting inwardly therefrom at right angles thereto pivotally mounted'in a suitable support 177 at the front of the circuit breaker, preferably adjacent the button 162 of the tripping rod 160. The support 177 may be firmly carried by a bracket 178 extending downwardly and outwardly from the side walls 20 of the centre compartment, see Figure 2. This shaft 176 is connected by an insulating block 179 to an upper shaft 180 of a crank 181. The crank normally hangs downwardly, and has a pin 182' connected by a universal joint 183 to the upper end of an inclined link 184, the lower end of which is connected by a pivot pin 186 to the lower end of a vertical block or link 187. The upper end of the last link is connected to a pin 191 carried by and extending transversely of the lower end 88 of lever 86. Link 184 is split so that link 187 fits therein. With this construction, link 184 is free to pivot towards and away from link 187 but it cannot swing laterally relative thereto or, in other words, these two links always lie in the same plane, as clearly shown in Figures 2 and 3.

Handle 175 and crank 181 normally hang downwardly, at which time the upper portion 87 of lever 86 presses pin 82 against stop 84. When the handle is rotated in a counter-clockwise direction, the crankpin follows the same course. This draws the lower end of lever 86 upwardly and moves the portion 87 of said lever away from pin 82. If link 83 is free at this time, spring 89 moves it with the lever portion.

When the handle and crank are in their normal positions, crankpin 182 is positioned to one side of a toggle This stop may be enline 'b passing through the axis of shaft 180 of the crank and that of the pivot pin 186, see the diagram in Figure 12. Further movement of the crank in a clockwise direction at this time is prevented by a suitable stop. In the illustrated example the invention, a stop 195 projects out-' wardly from support 177, see Figures 1 and 2, and is engaged by a lug 196 secured to handle 175. In order to swing the handle upwardly, it is necessary to move the crankpin over the toggle line, and this requires some little effort. In other words, the handle is firmly retained in its normal position by this arrangement and any upward pressure exerted by the lower end of lever 86 merely presses lug 196 against stop 195.

Figures 15 to 18 diagrammatically illustrate the operation of the linkage of this circuit breaker. Connector links '70 and 74 are arranged in an angle c extending in the direction away from the main pivot 22, while holding links 96 and 98 form an angle a opposed to the other angle and extending in the opposite direction. The apex of angle d (pin 97 and roller 99) is free to swing below the main pivot when tripping arm 148 is out of the way, but when the latter is in its normal position roller 99 cannot move downwardly, see Figures 3 and 15.

Figure 15 illustrates the main contacts in the closed position, and it shows the lines of force at this time. Main spring 43 is under compression, and auxiliary spring always urges the auxiliary arm 92 in a clockwise direction around pivot 24. At this time, the main spring urges the supporting component 28 in an anti-clockwise direction around main pivot 22, and this tends to move connector link 70 in the direction of arrow 210. The inner end of the auxiliary arm 92 tends to swing in the direction of arrow 211, and the combined forces tend to move con-' nector link 74 downwardly in the direction of arrow 212. Toggle links 78 and 83 are positioned to hold pivot 82 to the left of toggle line I between pivots 75 and 26. The downward force of link 74 presses pivot 82 against stop 84 so that the full force of springs 43 and 125 prevents the toggle links from moving back over toggle line f. In addition to this, any force resulting from a short circuit tending to move the contact block towards the open position is prevented from doing this by this linkage setup, and merely tends to move toggle links 78 and 83 farther from the toggle line thereof.

As links 74 and 78 are positioned so that pivot 75 is located to the left of toggle line g extending between pivots 73 and 82, the downward force of link 74 tends to move the holding link 98 in the direction of arrow 213. This tends to move the holding link 96 in the direction of arrow 215, but movement is prevented by the fixed pivot 22. The combined forces of links 96 and 98 tend to give a downward component in the direction of arrow 216 to pivot 97 and roller 99. As this roller is resting on the upper end of tripping arm 148, pivot 97 is unable to move at this time. No matter how much force is applied in an effort to open the contacts, the contact block 30 cannot move as long as the pivot 97 and roller 99 are held in place by the tripping arm, and since this force cannot impart any lateral component to the arm, the latter cannot be accidentally moved out of its position supporting the roller.

The breaker is tripped by rocking shaft 136 to move arm 148 from beneath pivot 97 and roller 99. This may be accomplished manually by pressing button 162 and rod inwardly to engage lug 153 connected to the shaft, or electrically by one of the relays 138. The relay is operated by a current load above a predetermined point. The operation of the relay moves plunger 142 upwardly to engage lug 144 and rock the tripping shaft. As the outer end of the tripping arm is curved with a true radius with shaft 136 as centre and bearing against roller 99, no excessive efiort is required to move said arm. Although the full pressure of springs 43 and 125 is applied to the curved upper end of the arm, no lateral component is imparted thereto so that the only opposition to the rocking I of the shaft is caused by spring 147 and the friction of the bearings supporting the shaft and those of roller 99. As the pressure of'the spring and the friction ofthese bearings are very little, the arm moves readily when the shaft is rocked either manually or automatically. Furthermore, the roller rotates at this time so that there is a minimum of friction. Immediately the corner 14% and the arm moves over line 15%, the full force of springs 43 and 125 force it to continue to move until it is stopped when lug 144 of the centre compartment engages stop 221 extending upwardly from a wall of said compartment.

As soon as pivot 5 7 is free, springs 43 and 125 force the links 74 and 78 to bow outwardly or, in other words, move farther away from toggle line g, as shown in Figure 16. This action is limited by component 28 engaging a stop 224 and by pin 82 as long as the latter is retained against stop 84, said stop being held in this position as long as handle 175 is hanging downwardly. At this time pm 182 is positioned to the left of line b, see Figure 12, so that pin 32 is firmly held against stop 84. Stop 224 may be formed by pressing inwardly a portion of one or both walls 20 of the centre compartment, see Figure 3 and 4. Contact block 36 is moved by this action well clear of the stationary contacts 50 and 51.

When it is desired to latch the breaker, operating handle 175 is turned almost half a revolution in an anti-clockwise direction. As previously described, this swings the lower end of lever 86 upwardly, moving the portion 87 thereof around latching pivot 26, see Figure 11. As spring 89 is connected to link 83, the latter is drawn in the same direction. The spring is strong enough to move pivot 82 away from stop 84 and across the toggle line 1 since there is very little resistance to the movement at this time. Spring 43 is not functioning since block 3%) is clear of the main stationary contacts. Figure 17 shows pivot 82 swung to its innermost position, at which time pivot 7 has moved towards and beyond tripping arm 148. As the operating handle is returned to its normal position, pivot 32 is moved back towards stop 84. During the first part of the return movement of this pivot, pivot 97 moves downwardly until roller 99 engages the upper end or" arm 148, see Figure 18. Further movement of the handle forces pivot 82 across toggle line 1 and back against stop 84. This action moves the contact block back to the closed position engaging the stationary main contact.

By referring to Figure 3 it will be seen that contact block 39 is moved outwardly by main spring 43 until pins 31 reach the outer ends of slots 34. This means that when the block engages the stationary contacts and 51, the component 28 continues to move until the main spring is considerably compressed. This takes place during the last part of the movement of the linkage back to the closed position. Spring 43 starts to be compressed as pivot 82 approaches the toggle line f. Thus, it requires considerable force to move said pivot over the toggle line. This is offset in some degree by the fact that as the angle between links 78 and 83 becomes greater, the smaller the torque required on link 83 to move pivot 82 over the toggle line.

Figures 12 to 14 diagrammatically illustrate the movement of the operating handle 175 and the elements associated therewith. In Figure 12, the handle is extending straight down, and pin 182 is to the left of toggle line b. The first part of the movement of the handle in an anti-clockwise direction, shifts the pin 182 across the toggle line to the position indicated in Figure 13. upward movement of the handle moves the links 184 and 187 in the same direction. As these links are so connected that they must always remain in the same plane relative to each other, the upper end of link 187 swings the lower end of lever 86 upwardly until it reaches the position shown in Figures 11 and 14. At this time, the linkage of the breaker has reached the position illustrated Further direction back to its normal position, the lower end of lever 86 is drawn downwardly, while the upper end of said lever presses the pin 82 back towards the stop 84 until said pin passes over the toggle line 7.

An anti-bounce arrangement is provided in order to prevent the main contact block 30 from bouncing towards the stationary main contacts when the circuit breaker is opened. In this example, the anti-bounce arrangement includes a latch 235 depending from a shaft 236 which is journalled in the side walls 20 of the centre compartment near the connector link 74, see Figures 3 and 4. A spring 238 tends to, rotate this shaft in an anticlockwise direction as viewed in Figure 3, and a stop 239 extending downwardly from the shaft limits this movement by engaging a lug 240 projecting inwardly from one of the compartment walls 20. This stop normally retains latch 235 in a substantially vertical position. Link 7-4 is provided with a horizontal stop pin 242 substantially midway between the ends thereof and in line with the latch.

When the circuit breaker is closed, links 74 and 78 are almost in a vertical position, as shown in Figures 3 and 15. However, when the breaker is tripped, links 74 and 78 how outwardly, and the former moves in such a way that the stop pin 242 brushes past latch 235. The latch swings outwardly against the tension of spring 238 at this time, and as soon as the pin clears the latch, the latter moves back over the top of the pin to prevent it from moving in an upward direction. When the breaker is in the fully open position, the latch is positioned immediately above the stop pin so that the main contact block cannot move towards the stationary contacts.

When the breaker is being latched, the pivot 82 is moved away from stop 84 in the manner described above. This action drawns pin 75 downwardly and inwardly which, in turn, moves the stop pin 242 inwardly clear of latch 235. Thus it will be seen that the latch cannot interfere with the closing of the breaker.

From the above, it will readily be seen that the breaker cannot be tripped by shock, jar or vibration, regardless of the load which it may be carrying at any time. The reason for this is that no matter what force tries to move the main contact block 30 away from the stationary contacts, it merely results in the pivot 82 being pressed against the stop 84. It is impossible for any tendency of the contact block to move away from the stationary contact to move the pivot 82 back across the toggle line 1.

An important feature of this breaker lies in the fact that very little effortis necessary to rotate the tripping shaft 136 and yet the latter cannot be accidentally rocked. All the pressure of springs 43 and is applied to the curved end of tripping arm 148 in the direction of the centre line so that no lateral component is imparted to thearrn by this force. As the outer end of this arm is curved with the centre of curvature coinciding with the axis of the tripping shaft, the latter may be rotated either by the tripping rod or by one of the overload relays without having to raise roller 99. Thus, only sufficient effort to overcome the pressure of spring 147 and the friction of the bearings of the shaft and the roller is required to trip the breaker. Furthermore, any increase in pressure on the outer end of the tripping arm resulting from a short circuit does not interfere with the operation of the tripping mechanism. Once the tripping arm has moved sufficiently to shift the edge 149a across the centre line 150, the pressure of springs 43 and 123 keeps the arm moving so that there is no danger of the mechanism stopping .in a partially unlatched position.

It does not matter how long the breaker remains in the closed or open position, nor what the atmospheric conditions are when it is in either position. It cannot help but open when the tripping shaft is rocked, or close when the operating handle is rotated upwardly and then downwardly in the manner previously described. When the shaft is rocked, the tripping arm is moved from beneath roller 99 so that there is nothing to retain the linkage in the closed position. Consequently, the linkage is bound to collapse under its own weight and under the action of springs 43 and 128. The leverage afforded by the operating handle and the linkage connected thereto ensures easy closing of the breaker.

What I claim as my invention is:

1. In an electric circuit breaker having stationary main contacts, a spring-loaded main contact block, linkage carrying the block for moving the latter towards and away from the stationary contacts, an auxiliary spring connected to the linkage, said block spring exerting a pressure through the linkage to keep the block against the stationary contacts, two substantially aligned pivotally connected toggle links beneath and extending to wards the linkage, the upper end of said links being pivotally connected to the linkage and the lower end thereof being mounted on a fixed pivot, a stop against which the pivot between the toggle links is maintained to one side of a toggle line between the outer pivots of said links under the pressure of the block and auxiliary springs, and means beneath the linkage beside the toggle links for removably holding said linkage in position with the block against the stationary contacts, said holding means being movable to allow the linkage to collapse, whereby the block and auxiliary springs force said block away from the stationary contacts.

2. In an electric circuit breaker having stationary main contacts, a spring-loaded main contact block, linkage carrying the block for moving the latter towards and away from the stationary contacts, an auxiliary spring connected to the linkage, said block spring exerting a pressure through the linkage to keep the block against the stationary contacts, two substantially aligned pivotally connected toggle links beneath and extending towards the linkage, the upper end of said links being pivotally connected to the linkage and the lower end thereof being mounted on a fixed pivot, a stop against which the pivot between the toggle links is maintained to one side of a toggle line between the outer pivots of said links under the pressure of the block and auxiliary springs, a tripping arm beneath and removably supporting a portion of the linkage, and means for displacing the tripping arm to allow said linkage portion to move out of position and cause the linkage to collapse, whereby the block and auxiliary springs force said block away from the stationary contacts.

3. An electric circuit breaker as claimed in claim 2 including means for restoring the linkage portion on the tripping arm and resetting the linkage with the block against the stationary contacts by moving the pivot between the toggle links away from its stop and then returning said pivot to the stop across the toggle line.

4. In an electric circuit breaker having stationary main contacts, a pivotally-mounted supporting component, a main contact block movably mounted in the component, spring means normally urging the block outwardly of the component, linkage connected to the component normally holding the block against the stationary contacts, a pivotally-mounted arm connected at one end to the linkage, spring means tending to swing the arm around its pivot, said block spring exerting a pressure through the linkage to keepthe block against the contacts, two substantially aligned pivotally connected toggle links beneath and extending towards the linkage, the upper end of said links being pivotally connected to the linkage and the lower end thereof being mounted on a fixed pivot, a stop against which the pivot between the toggle links is maintained to one side of a toggle line between the outer pivots of said links under the pressure of the block and auxiliary springs, and means for removably holding the linkage in position with the block against the stationary contacts, said holding means being movable to allow the linkage to collapse, whereby the block and auxiliary springs force said block away from the stationary contacts.

Cit

5. In a circuit breaker having stationary contacts, spaced main and latching pivots fixed relative to each other, a supporting component mounted on the main pivot, a main contact block movably mounted on the component, spring means normally urging the block out wardly of the component, connector links pivotally connected together arranged in an angle extending away from the main pivot at their inner ends, the outer end of one connector link being pivotally connected to the component spaced from the main pivot, two substantially aligned toggle links pivotally connected together at their inner ends, the outer end of one toggle link being pivotallyconnected to the outer end of the other connector link and the outer end of the other toggle link being mounted on the latching pivot, auxiliary spring means tending to move the pivot between the connector links to straighten the latter out, said block spring means exerting a pressure through the links to keep the contact block against the stationary contacts, a stop against which the pivot between the toggle links is maintained to one side of a toggle line between the outer pivots of said links under the pressure of the block and auxiliary spring means, holding links pivotally connected together at their inner ends and arranged in an angle opposed to and extending away from the connector link angle, the outer end of one holding link being connected to the main pivot, and the outer end of the other holding link being connected to the pivot between the connected connector and toggle links, and means for removably retaining the holding links in a position with the block against the stationary contacts, said connected connector and toggle links being substantially aligned at this time on the side of a toggle line between the outer pivots thereof remote from the main pivot, said retaining means being movable to free the holding links and aliow the two spring means to move the block away from the contacts.

6. An electric circuit breaker as claimed in claim 5 in which the retaining means comprises a pivotally-mounted tripping arm against the end of which the pivot of the holding links rests under pressure of the two spring means, said arm being spring-loaded normally to remain in this position.

7. An electric circuit breaker as claimed in claim 5 in cluding a roller carried by the pivot of the holding links, and in which the retaining means comprises a tripping arm pivotally mounted at one end positioned so that the roller I normally rests on its free end.

8. An electric circuit breaker as claimed in claim 7 in which the free end of the tripping arm is curved with its centre of curvature coinciding with the pivot of the arm.

9. An electric circuit breaker as claimed in claim 8 in which one side of the tripping arm and the curved end thereof form a sharp edge at one side of said curved end.

10. An electric circuit breaker as claimed in claim 6 including means for manually moving the tripping arm away-from the link of the holding links.

11. An electric circuit breaker as claimed in claim 6 including a relay to be connected to the circuit controlled by th breaker, a plunger moved by the relay when the current in the circuit reaches a predetermined point, the movement of said plunger moving the tripping arm away from the pivot of the holding links.

12. An electric circuit breaker as claimed in claim 5 including anti-bounce means comprising a spring-loaded latch mounted near the connector link connected to the.

toggle link, and a stop mounted on said toggle link, said stop being engaged by the latch when the contact block is moved away from the stationary contacts to prevent 11 V I means, and including means for returning the contact block against the contacts by moving the pivot between the toggle links across the toggle line thereof to move the holding links back on to the retaining means and then moving the pivot of the toggle links back across said toggle line.

14. An electric circuit breaker as claimed in claim 13 in which the means for returning the contact block against the contacts comprises a lever mounted on the latching pivot, said lever having a portion movably connected to the toggle link mounted on the latching pivot and another portion projecting from the opposite side of said pivot, and handle means connected to the latter lever portion to move the otler lever portion and shift the toggle links across the toggle line thereof.

15. In a circuit breaker having stationary contacts, main, auxiliary and latching pivots fixed relative to each other and arranged substantially in a triangle, a supporting component mounted on the main pivot, a main contact block movably mounted on the component, spring means normally urging the block outwardly of the con ponent, connector links pivotally connected together arranged in an angle extending away from the main pivot at their inner ends, the outer end of one connector link being pivotally connected to the component spaced from the main pivot, two substantially aligned toggle links pivotally connected together at their inner ends, the outer end of one toggle link being pivotally connected to the outer end of the other connector link and the outer end of the other toggle link being mounted on the latching pivot, an arm mounted on the auxiliary pivot and having one end connected to the pivot between the connector links, spring means pressing against the opposite end of the lever tending to swing the latter around its pivot, said arm under the spring pressure tending to straighten the connector links out, said block spring means exerting a pressure through the links to keep the contact block against the stationary contacts, a stop against which the pivot between the toggle links is maintained to one side of a toggle line between the outer pivots of said links under the pressure of the block and auxiliary spring means, holding links pivotally connected together at their inner ends and arranged in an angle opposed to and extending away from the connector link angle, the outer end of one holding link being connected to the main pivot, and the outer end of the other holding link being connected to the pivot between the connected connector and toggle links, and means for removably retaining the holding links in a position with the block against the stationary contacts, said connected connector toggle links being substantially aligned at this time on the side of a toggle line between the outer pivots thereof remote from the main pivot, said retaining means being movable to free the holding links and allow the two spring means to move the block away from the contacts.

16. In an electric circuit breaker having stationary main contacts, a spring-loaded main contact block, linkage carrying the block for moving the latter towards and away from the stationary contacts, an auxiliary spring connected to the linkage, said block spring exerting a pressure through it e linkage to keep the block against the stationary contacts, two substantially aligned pivotally connected toggle links extending upwardly towards the linkage, the upper end of said links being pivotally connected to the linkage and the lower end thereof being mounted on a fixed pivot, a stop against which the pivot between the toggle links is maintained to one side of a toggle line between the outer pivots of said links under the pressure of the block and auxiliary springs, a trip ping arm removably supporting a portion of the linkage,

-means for displacing thetripping arm to allow sai linkage portion to move out of position and cause the link.- age to collapse, and means connected to one of the toggle links for restoring said linkage portion to its position supported by the tripping arm.

essence 17. An electric circuit breaker as claimed in claim 16 in which the means for restoring the linkage portion comprises a lever swingably mounted on the pivot of the outer end of the lower toggle link, said lever having an upper end normally pressing the lower toggle link into a position with the pivot between it and the upper toggle link against the stop, means yieldably connecting the upper end of the lever to the lower toggle link, and means for lifting the lower end of the lever to move the pivot of the toggle links away from the stop and returning the linkage portion to its position supported by the tripping arm.

18. An electric circuit breaker as claimed in claim 17 in which the means for lifting the lower end of the lever comprises a rotatably-mounted shaft, an operating arm fixed to said shaft, a crank rotatably connected to the arm shaft, a pin on the crank, a link connected at one end by a universal joint to the pin, a second link connected at one end to the opposite end of the first link, said links extending in substantially the same direction, means retaining the first and second links in the same plane relative to each other, and means pivotally connecting the opposite end of the second link to the lower end of the lever.

19. An electric circuit breaker as claimed in claim 18 including a stop for limiting the movement of the crank over a toggle line extending through the axis of rotation of the crank and the centre of the pivotal connection of the first and second links.

20. in a circuit breaker having stationary contacts, a main pivot, a supporting component mounted on and extending upwardly from the main pivot, a spring-loaded main contact block mounted on the component near the upper end thereof and normally bearing against the stationary contacts, connector links pivotally connected together arranged in an angle extending away from the main pivot at their inner ends, the outer end of one connector link being pivotally connected to the component spaced from the main pivot, holding links pivotally connected together at their inner ends, the outer end of one holding link being connected to the main pivot, the other holding link extending substantially in the same direction as the first holding link past the main pivot and being pivotally connected to the outer end of the other connector link, said holding links forming an acute angle opposed to and extending away from the connector link angle, means movably supporting the joined ends of the holding and said other connector links, tripping means removably supporting the joined ends of the two holding links, and auxiliary spring means tending to move the pivot between the connector links to straighten the latter out.

21. In a circuit breaker having stationary contacts, a main pivot, an auxiliary pivot above and to one side of the main pivot, a latching pivot below and to the same side of the main pivot, a supporting component mounted on and extending upwardly from the main pivot, a spring-loaded main contact block mounted on the component near the upper end thereof and normally bearing against the stationary contacts, pivotally connected connector links having one end pivotally connected to the component spaced from the main pivot and arranged in an angle extending away from the latter towards the auxiliary pivot, holding links pivotally connected at an acute angle oppose to and extending away from the connector link angle, one end of said holding links being connected to the main pivot and the other end thereof pivotally connected to the free end of the connector links, means movably supporting the joined ends or the holding and connector links, tripping means removably supporting the joined end of the holding links, an auxiliary arm mounted on the auxiliary pivot extencL ing towards and pivotally connected to the connected ends of the connector links, and spring means swinging the '13 auxiliary arm around its pivot resiliently to press the connector links inwardly towards the main pivot.

22. A circuit breaker as claimed in claim 21 in which the tripping means for supporting the joined ends of the holding links comprises a pivotally-mounted tripping arm extending towards and supporting said holding links at the pivotal connection thereof and including means for moving the arm from beneath the holding links to permit all the joined links to collapse.

23. A circuit breaker as claimed in claim 21 including a roller carried by the pivot at the connection of the two holding links, and in which the tripping means for supporting the joined ends of said holding links comprises a tripping arm mounted on a rotatably mounted tripping shaft to one side of the axis of the latter, said arm extending upwardly towards and supporting said roller, the upper end of said arm being curved with its centre of curvature coinciding with the shaft axis.

24. A circuit breaker as claimed in claim 23 in which one side of the tripping arm and the curved end thereof form a sharp edge at one side of said curved end, and

14 the point of contact of the curved end and the roller normally being near said sharp edge.

25. A circuit breaker as claimed in claim 21 in which the means movably supporting the joined ends of the holding and connector links comprises two substantially aligned pivotally connected toggle links, the outer end of one link being pivotally connected to said joined ends of the holding and connector links and the outer end of the other toggle link being mounted on the latching pivot, and a stop against which the pivot of the toggle links is normally maintained to one side of a toggle line between the outer pivots of said links.

References Cited in the file of this patent UNITED STATES PATENTS 1,761,724 Hamlyn et al. June 3, 1930 1,953,789 Thumim Apr. 3, 1934 2,141,272 Hill Dec. 27, 1938 2,227,160 Seaman Dec. 31, 1940 2,322,301 Lindstrom et al June 22, 1943 2,647,182 Florschutz et al. July 28, 1953 

